Rotary pump or motor



1968 L. H. REIMEIR ETAL 3,4

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 1' fzgui rINVENTORS LEONARD H. RE/MER EDWARD A. PR/JATEL ATTORNEYS Dec. 17, 1968RElMER ETAL 3,416,459

ROTARY PUMP 0R MOTOR Filed May 24, 1966 5 Sheets-Sheet 2 F- ?j IINVENTORS LEONARD hL-RE/MER EDWARD A. PR/JATEL VBY ATTORNEYS Dec. 17,1968 H. REIMER ETAL 3,

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 3 INVENTORS.LEONARD h. RE/ME'R EDWARD A. PR/c/ATEL ATTORNEYS 1968 1.. H. REIMER ETAL3,

ROTARY PUMP OR MOTOR Filed May 24, 1966 r 5 Sheets-Sheet 4- ATTORNEYSDec. 17, 1968 L. H. REIMER ETAL 3,415,459

ROTARY PUMP OR MOTOR Filed May 24, 1966 5 Sheets-Sheet 5 INVENTORSLEONAR H. REM/ER EDWARD A. PR/ 1 EL ATTORNEYS United States Patent3,416,459 ROTARY PUMP 0R MOTOR Leonard H. Reimer and Edward A. Prijatcl,Lyndhurst,

Ohio, assignors to Parker-Hannifin Corporation, Cleveland, Ohio, acorporation of Ohio Filed May 24, 1966, Ser. No. 552,462 13 Claims. (Cl.103126) ABSTRACT OF THE DISCLOSURE A gear pump characterized by apassage in the wall of the pump cavity for extending the high pressurezone over a major portion of the cavity, and a flexible wear plate inthe housing having an inner face in juxtaposition to the gear faces andan outer face contacted by a seal to provide a compartment opposite thehigh pressure zone and an intermediate pressure zone in the cavity towhich high pressure fluid is introduced for providing a fluid pressurebalance on the plate opposite the high pressure zone and an overbalanceopposite the intermediate pressure zone tending to flex the plate intosealing engagement with the gear faces.

The present invention relates to a rotary pump or motor and moreparticularly to a gear pump or motor having means for sealing the gearfaces to prevent internal fluid leakage between the high and lowpressure zones, and to minimize wear.

Sealing of gear type pumps or motors with the use of a flexible wearplate that is maintained in sealed engagement with the gear faces byintroducing fluid pressure behind the plate is generally old and wellknown. In such known constructions the pressure behind the flexibleplate is higher than the pressure in the gear cavity along a substantialportion of the plate so that the plate is maintained in sealing contactwith a large portion of the gear side faces. Although this provides aneffective seal it also results in considerable friction and hencereduced efliciency.

An object of the present invention is to utilize fluid pressure to pressthe flexible plate into sealing contact with the gear faces along only arelatively small area, the remaining portions of the plate that areopposite the gear faces having either the same fluid pressure on the twosides thereof, or having a slight unbalance in a direction away from thegear faces, so that such remaining portions of the plate aresubstantially fluid pressure balanced to avoid being pressed against thegear side faces by fluid pressure whereby friction therebetween issubstantially eliminated.

Generally, the above object is attained by substantially balancing aportion of the plate with low pressure and by providing a passage in thewall of the housing for causing high fluid pressure in a major portionof the gear cavity to act on the front side of the flexible wear plateand by providing a compartment on the back side of the flexible wearplate that is opposite such major portion of the gear cavity and that isslightly larger in area than said major portion so as to overlap arelatively small portion of the cavity that is subjected to intermediatepressure whereby the plate will be overbalanced to flex into sealingcontact with the gear faces only at such intermediate pressure zone.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed draw- Patented Dec. 17, 1968 ing setting forth in detailcertain illustrative embodiments of the invention, these beingindicative, however, of but a few of the various ways in which theprinciples of the invention may be employed.

In such annexed drawing:

FIG. 1 is a side elevation view of a preferred form of pump or motorconstructed in accordance with this invention;

FIG. 2 is an end elevation view of the pump of FIG. 1 as seen from theright side thereof looking into the high and low pressure ports;

FIG. 3 is an enlarged longitudinal section taken on the plane of theline 3-3 of FIG. 2;

FIG. 4 is an end elevation view on a reduced scale of the pump or motorof FIG. 3 with the back cover assembly removed as seen from the plane ofthe line 4-4;

FIG. 5 is an enlarged fragmentary horizontal section taken on the planeof the line 5-5 of FIG. 4;

FIG. 6 is a fragmentary transverse section taken on the plane of theline 6-6 of FIG. 3;

FIG. 7 is an end elevation view on a reduced scale of the front coverassembly as seen from the plane of the line 77 of FIG. 3, showing theconfiguration of the wear plate which is accurately located in a recessin the inner face of the front cover assembly;

FIG. 8 is a perspective view similar to FIG. 7, but with the wear plateremoved and the heat shield and gasket partially broken away to show theseal thereunder;

FIG. 9 is an exploded perspective view of the seal, gasket, heat shield,and wear plate which are adapted to be inserted in the front coverassembly;

FIG. 10 is an enlarged longitudinal section similar to FIG. 3, but ofanother form of pump or motor in accordance with this invention;

FIG. 11 is a transverse vertical section taken on the plane of the line11-11 of FIG. 10; and

FIG. 12 is an exploded perspective view similar to FIG. 9 butillustrating the seal-gasket-heat shield of FIGS. 10 and 11 with amodified form of wear plate.

Referring now in detail to the drawing, and first to FIGS. l-9, a formof rotary gear pump in accordance with this invention is generallyindicated at 1 and comprises a housing 2 which may include a front coverassembly 3 and back cover assembly 4 with a center section 5 sandwichedtherebetween and secured together as by means of suitable bolts 6 andlocated by dowels 7.

Within center section 5 is a pump cavity 8 of figureeight configurationsfor receipt of a pair of pumping gears 9 and 10 supported by shafts 11and 12 journaled in stationary sleeve bushings 13 in the front and rearcover assemblies 3 and 4. Pump cavity 8 includes low and high pressurechambers or zones 15 and 16 respectively communicating with inlet andoutlet ports 17 and 18 in the back cover assembly 4. One of the gearshafts 11 has a longitudinal bore 20 therethrough for equalizing thepressure at opposite ends of the shaft 11, while the other gear shaft 12extends outwardly through the front cover assembly 3 for connection to asuitable prime mover, with a rotary seal 21 surrounding the gear shaft12 to preclude leakage of fluid therealong. A passage 22 interconnectsthe shaft receiving bores 23 in the front cover assembly 3.

Leakage of fluid between the mating surfaces of the front and back coverassemblies 3 and 4 center section 5 is precluded by a pair of O-ringseals 25 disposed in ovaloidal grooves 26 in the inner faces of thefront and back cover assemblies 3 and 4 which surround the pump cavity 8and inlet and outlet chamber 15 and 16.

Inner face 27 of one of the cover assemblies 4 is flat for engagement bythe adjacent gear faces 28, while the inner face 29 of the other coverassembly 3 has an ovaloidal recess 30 therein that receives a similarlyshaped thin wear plate 31 for engagement with the other gear faces 24.Recess is radially spaced from the adjacent groove 26 to provide agroove wall portion 26a for confining O-ring 25. The wear plate 31 maybe a laminant consisting of an inner plate 32 of bronze or like metaland a steel backing 33 with holes 34 through the wear plate 31 forpassage of the gear shafts 11 and 12.

The back face of the wear plate 31 may be divided into a pair ofdifferent sized compartments 35 and 36 by a racetrack type seal 37 withgasket 38 and heat shield 39 interposed between the seal 37 and wearplate 31. All of these parts, the seal 37, gasket 38, and heat shield 39have an outer configuration identical to the wear plate 31, but they areall skeletonized to provide a circumferentially continuous outer margin40 and a pair of inner continuous circular portions 41 connected to theouter margin 40 by two angularly disposed fences 42 and 43 andinterconnected together by a central fence 44. In this instancecompartment 35 comprises compartment sections 35a, 35b, and 350 becausethese sections are communicated to each other by cutouts 59a and 60a infence portions 59 and 60 of seal 37. The bottom of the recess 30 iscomplementally grooved at 45 for receipt of the seal 37, gasket 38, andheat shield 39, but with the heat shield 39 extending slightly out ofthe groove 45 into the recess 30 as shown in FIGS. 3 and 8 to definewith the bottom of the recess 30 and the back face of the wear plate 31the various compartments 35 and 36. The seal 37 is made of a suitableresilient material such as rubber, while the gasket 38 is preferablymade of saturating paper and the heat shield 39 of cotton phenolic,although of course other suitable materials may be used.

Openings 46 and 47 are provided in the wear plate 31 for communicatingthe compartments 35 and 36 with high pressure chamber 16 and lowpressure chamber 15 respectively. The pressure Within the compartment 35acts on the. wear plate 31 to urge the same toward the adjament gearfaces 32 in opposition to the fluid pressure within the pump cavity 8,including the pressure of the fluid within the gear teeth pockets andthe fluid film that exists between the side faces of the gears and thewear plate, that is urging the wear plate in a direction away from thegears. Ordinarily, the pressure in the gear cavity increasesprogressively from the low pressure chamber 15 to the high pressurechamber 16 and with only a single pressure compartment 35 incommunication with high pressure chamber 16 there would be a balancingof the pressures on opposite sides of the plate at chamber 16 and aprogressive overbalance or differential pressure pushing the platetoward the gears in the region along the unmeshed gear teeth betweensuch high and low pressure chambers 16 and 15. Such progressivedifferential flexes and presses the plate tightly against the gear teethso as to effectively seal their side faces but also results in excessivefriction and wear of the plate.

In the FIGS. 1 to 9 form high pressure chamber 16 is extended to nearlythe area of compartment 35 by providing a radial relief in the pumpcavity wall around the gears 9 and 10. This relief 55 provides a spacebetween the outer ends of the gear teeth and pump cavity 8 to connectthe gear tooth pockets in this region with high pressure outlet 18 sothat these tooth pockets and the fluid film between the adjacent gearteeth and plate 31 have the same high pressure as in chamber 16. Thus,where the compartment 35 and high pressure chamber 16 are opposite eachother the fluid pressure forces on the wear plate 31 are balanced.Between the ends 55a of relief 55 and the corners 15a of low pressurechamber 15 the radially outer faces of the gear teeth have a very closefit with the transverse wall of pump cavity 8 and the pressure in thegear teeth pockets between corners 15a and relief ends 550, as well asthe fluid film pressure between the adjacent gear teeth of the wearplate, progressively increases the wear from the pump low pressure tothe pump high pressure to provide a zone of increasing pressure incavity 8. Compartment 36 has a portion thereof opposite low pressurechamber 15 and has other portions B opposite such zones of increasingpressure in cavity 8. The pressure in compartment 36 is uniformthroughout and is the same as in low pressure chamber 15. The fluidpressure on the opposite sides of wear plate in the region of lowpressure chamber 15 are therefore balanced but the fluid pressures incavity 8 in the regions designated B are somewhat higher than in thecorresponding portions of compartment 36 and therefore tend to flexplate 31 away from the gear side faces in such B regions andconsequently there is little or no friction between the gear side facesand the wear plate in such regions. Even though there is a tendency forthe fluid pressure to lift the wear plate from the gears at such Bregions, the plate actually remains closely adjacent the gear side facesbecause of its inherent resistance to flexing.

In the region of compartment 35b designated A, the fluid is under thesame high pressure as the remainder of compartment 35b but the pressurein the corresponding portion of the cavity 8 is somewhat less, that is,it is an intermediate pressure, because of the above described gradientor progressive increase in pressure between cavity corners 15a andrelief ends 55a. This provides a differential or overbalance pressure onthe portion of plate 31 in regions A tending to press the same againstthe gear teeth side faces to provide an effective seal therebetween.

Thus, as described above, reliefs 55 and compartments 35 and 36cooperate to provide a pump arrangement in which most of the area of thewear plate is either fluid pressure balanced or slightly fluid pressureoverbalanced in a direction tending to unseat the plate from the gearteeth side faces and only a small area A of the plate is subject to adifferential in compartment pressure as compared to correspondinglylocated pump cavity pressure that acts to press such small area of theplate into sealing contact with the gear teeth side faces. Because thereis high pressure in the channel of fences 42 and an intermediategradient pressure in cavity 8 therebeneath there is also an overbalanceforce on the wear plate in this location. In the manner described, thegear side faces are effectively sealed between the low and high pressurechambers 15 and 16 at a relatively small area of the plate as thatfriction and wear between the plate and gear side faces is minimized.

For maintaining the seal 37, gasket 38 and heat shield 39 in fluid tightengagement with the wear plate 31 to preclude leakage of fluid betweencompartments 35 and 36, the outer face of the seal 37 has a compositegroove or channel 57 formed therein which may be supplied with highfluid pressure through additional openings 58 in the wear plate 31communicating with cutouts 59a and 60a of fence portions 59 and 60 onthe seal 37 located in complemental grooves 61 in the front coverassembly 3. Alternatively, the additional wear plate openings 58 may beeliminated, since high fluid pressure will still be supplied to the sealchannel 57 from the compartment 35 via the grooves 61 in the front coverassembly 3 and cutouts 59a and 60a. Or the additional fences 59 and 60may be left intact and the seal 37, gasket 38, heat shield 39' and Wearplate 31' provided with aligned apertures 62 communicating the sealchannel '57 with high pressure chamber 16 in the pump cavity 8', as inthe FIGS. 10 and 11 embodiment.

As seen in FIGS. 3 and 5, the grooves 45, 61 in the front cover assembly3 are stepped at 63, while the inner and outer seal lips 64 and 65 whichdefine the seal channel 57 are of the same length, However, the outerlip 65 is thicker than the inner lip 64 and is squeezed somewhat byengagement with the top 66 of the step 63 to provide a slight mechanicalloading of the wear plate 31 against the center section 5 and form apressure pocket 67 in which the pressure expands the lips 64 and 65 intosealed engagement with the walls of the grooves and, in addition,applies a further sealing force against the wear plate 31.

The openings 46 and 47 in the wear plate 31, besides supplying high andlow fluid pressure to the compartments 35 and 36 as aforesaid, alsoprovide anti-trapping reliefs to facilitate engagement and disengagementof the pump gears 9 and 10. Moreover, depressions 68'may be formed inthe inner face of the wear plate 31 to provide lubrication for the gearfaces during operation.

In FIGS. 10 and 11 there is illustrated another form of pump 1 inaccordance with this invention which is quite similar to the pump 1already described and accordingly like reference numerals followed by aprime symbol are used to designate like parts. However, the large highpressure compartment 35' is divided into three smaller compartments 70,71 and 72 preferably by leaving the seal fences 59' and 60' intact andproviding corresponding fences 59 and 60' on the gasket 38' and heatshield 39. Moreover, the relief 55 has been eliminated and instead theadjacent gear teeth pockets and side faces are communicated with highpressure chamber 16" by means of sickle shaped grooves 75 in the innerface of the back cover assembly 4' which extend from chamber 16 to aboutthe middle of the intermediate compartments 71 and 72. Apertures 76 inthe wear plate 31' interconnect the sickle grooves 75 and intermediatecompartments 71 and 72 across the rotating gears. As in the case ofreliefs 55, sickle grooves 75 eliminate rising pressure in the geartooth pockets adjacent thereto and the pressure in such pockets and thefluid film pressure between the adjacent gear teeth side faces and thewear plate will be the same as in high pressure chamber 16. In this casethe fluid pressures acting on opposite sides of the wear plate will bebalanced in the regions of compartment 35' and those portions ofcompartments 71, 72 to the right of the portions designated C in FIG. 11and will be overbalanced in a direction to press the plate against thegears in such portions designated C. The fluid pressure efiect on theplate in the region of compartment 36 is the same as in connection withcompartment 36 of'FIG. 6.

In FIG. 12 the seal 37', the gasket 38 and the heat shield 33' are thesame as in FIGS. 10 and 11 and either the sickle grooves 75 or therelief 55 may be used in the housing. The wear plate 80, however,differs from the wear plate 31' in that the slot 46 on the high pressureside has been omitted and slots 81, 82 are substituted. These slots 81,*82 :are over and extend to either side of fences 59', 60 so as todirect high pressure fluid from pump cavity 8 to compartments 71, 72 and75. The fluid pressures acting on wear plate 80 in the regions of thesecompartments are thus the same as in connection with FIG. 11. Thus inall forms of the invention herein disclosed, substantially equal andrelatively large areas on opposite sides of the wear plate 31, 31' or 80are exposed to high outlet pressure so as to be fluid pressure balanced,and relatively small areas at intermediate pressure zones A or C of thepump cavity are overbalanced by outlet pressure in the opposed portionsof the compartment behind the wear plate. In addition, opposite areas ofother portions of the plates are exposed to either low inlet pressure orto pressures somewhat higher than inlet pressure whereby such otherportions are either balanced or have a slight tendency to move away fromthe gear side faces. In this way, the wear plate 31, 31', or '80 isflexed by moderate fluid pressure differential acting on relativelysmall areas against the gear faces to effect proper sealing but withoutexcessive friction and wear.

All three forms of the invention permit rotation of the driving gear 10in either direction without substituting new parts. When the parts areassembled as illustrated in the drawings, driving gear 10 rotates in aclockwise direction as viewed in FIG. 4 and driven gear 9 rotates in acounterclockwise -direction. To have driving gear 10 rotatecounterclockwise it is only necessary to switch places with gear 9. Todo this in the FIG. 1-9 form, for example, cover 3, seal 37, heat shield38, gasket 39 and wear plate 31 are first removed, these parts remainingtogether during removal.

Gears 5 and 10 are then interchanged. Seal 37, heat shield 38, gasket 39and wear plate 31 are then rotated within cover 3 and the cover, withthese parts therein, is rotated 180 and reassembled against centersection 5. Now driving gear 10 is in the upper position, as viewed inFIG. 4, and is rotated counterclockwise for pumping fluid from inletchamber 15 to outlet chamber 16. The wear plate, seal, heat shield, andgasket are in their original positions relative to center section 5 andtherefore fluid pressure will act thereon in the same manner as alreadydescribed.

Other modes'of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims, or the equivalent ofsuch, be employed.

We, therefore, particularly point out and distinctly claim as ourinvention: 1

1. A gear pump comprising a housing having a cavity that includes inletand outlet chambers, gears rotatable in said cavity to pump fluid fromthe inlet chamber to the outlet chamben a wear plate in the housinghaving an inner face adjacent one side of said gears, seal means in saidhousing contacting the outer face of said wear plate and forming withthe same a plurality of compartments, said seal meanshaving a channeltherein opening away from the wear plate, passage means forcommunicating said compartments with selected zones of said pump cavity,and aligned passages through said wear plate and the bottom wall'of saidchannel for conducting fluid from said outlet chamber to said channelwhere it exerts pressure on said seal means urging the same into contactwith the wear plate.

2. The pump of claim 1 in which there is only a single passage throughthe bottom wall of said channel.

3. A rotary pump comprising a housing having a cavity including inletand outlet ports, intermeshing gears rotatable in said cavity togenerate pressure influid conveyed thereby from said inlet port to saidoutlet port, a flexible wear plate in said housing having an inner facein juxtaposition to adjacent gear faces, skeletonized seal means insealed contact with said housing and with the outer face of said wearplate for providing between said housing and said wear plate at leasttwo compartments in fluid communication with the fluid pressure in saidoutlet port and with the fluid pressure in said inlet port respectively,the wall of said cavity removed from said wear plate having passagemeans extending the high pressure zone of said cavity from said outletport around a major portion of the peripheral portions of said gearsadjacent to successive intermediate pressure and low pressure zonesextending from said high pressure zone to said inlet port, thecompartment in communication with said outlet port being oppositetojsaid high pressure zone and circumferentially overlapping saidintermediate pressure zones, and the compartment in communication withsaid inlet port being opposite to said low pressure zone, whereby saidwear plate is pressure balanced in said high pressure zone, pressureoverbalanced in the portions which overlap said intermediate pressurezones, and pressure under balanced in said low pressure zone, thepressure overbalancing being in relatively small areas of said wearplate to flex the latter thereat into sealing engagement with theadjacent gear faces there-at.

4. A gear pump comprising a housing having a cavity, gears rotatable insaid cavity to provide adjacent intermediate and high fluid pressurezones in said cavity, a flexible wear plate in said housing having aninner face in juxtaposition to adjacent gear faces, passage means in thewall of said cavity removed from said wear plate for extending said highpressure zone over a major portion of said cavity, seal means in saidhousing contacting the outer face of said wear plate for providingcompartment means opposite to said high pressure and intermediatepressure zones, and means for introducing high pressure fluid from saidhigh pressure zone into said compartment means whereby the portion ofsaid plate opposite said high pressure zone of said cavity is fluidpressure balanced and the portion of said plate opposite saidintermediate pressure zone is overbalanced so as to flex said latterportion of said plate into sealing engagament with said gear faces.

5. The pump of claim 4 wherein said passage means comprises a radialrelief in the peripheral wall of said cavity.

6. The pump of claim 4 wherein said passage means comprises a grooveformed in the wall of said cavity that is opposite said wear plate.

7. The pump of claim 4 wherein said compartment means comprises separatesections, and there are apertures in said wear plate communicating saidcompartment sections with said high pressure zone.

8. The pump of claim 4 wherein said compartment means comprises separatesections, and there are slots through said wear plate each connectingtwo of said sections with said high pressure zone.

9. The pump of claim 4 wherein said seal means is skeletonized toprovide said compartment means, there is a channel in the back face ofsaid seal means which is supplied with fluid from said high pressurezone for maintaining said seal means in fluid-tight engagement with saidwear plate, and aligned apertures are provided in said seal means andwear plate for supplying such fluid from said high pressure zone to saidchannel as aforesaid.

10. The pump of claim 4 wherein said seal means is skeletonized toprovide said compartment means, there is a channel in the back face ofsaid seal means which is supplied with fluid from said high pressurezone for maintaining said seal means in fluid-tight engagement with saidwear plate, portions of said seal means are cut away through saidchannel, and there are apertures in said wear plate in alignment withsaid cutaway portions for supplying fluid from said high pressure zoneto said channel through said cutaway portions.

11. The pump of claim 3 wherein said seal means is disposed in a groovein said housing, and there are aligned passages in said plate and sealmeans for conducting fluid from said high pressure zone of said cavityto said groove to urge said seal means against the outer face of saidwear plate, said seal means being of channel-shaped crosssectionproviding axial lips which are retained in sealed engagement with theside walls of said groove by such fluid pressure in said groove.

12. The pump of claim 3 wherein said lips are of substantially equallength and said groove has a stepped bottom wall arranged to axiallysqueeze one of said lips between said bottom wall and the outer face ofsaid wear plate, the other of said lips being spaced from said bottomwall, and said one lip being radially thicker than said other lip.

13. The pump of claim 3 wherein said compartment in communication withsaid outlet port circumferentially overlaps only a portion of saidintermediate pressure zones, and said compartment in communication withsaid inlet port circumferentially overlaps another portion of saidintermediate pressure zones, whereby said wear plate is pressureoverbalanced in the portion of said intermediate pressure zones oppositesaid compartment in communication with said outlet port and pressureunderbalanced in the portion of said intermediate pressure zonesopposite said compartment in communication with said inlet port.

References Cited UNITED STATES PATENTS 2,644,701 7/1953 Flick 277205 XR2,809,592 10/1957 Miller et a1. 2,993,450 7/1961 Weigert. 3,057,30310/1962 Lauck. 3,101,673 8/1963 Clark et :11. 3,153,371 10/1964 Miller.3,294,029 12/1966 Clark et al.

FOREIGN PATENTS 1,121,180 7/1956 France.

FRED C. MATTERN, 111., Primary Examiner.

T. R. HAMPSHIRE, Assistant Examiner.

